@browallace that is the sucky thing about cats not necessarily I have seen them glow red and not pop a code (it was not a rover)

 

Aside from the drive shaft are there other components that would be acutely effected by clogged cats? Sometimes after I drive I can smell hot rubber. Could this be cat/exhaust hangers getting impacted by the hot cats?

 

Nope. No hangers near the cats. Sounds like you need to take some time and crawl around with a flashlight and give a visual inspection and see if anything is loose or rubbing that shouldn't be.

 

Could it be the rubber driveshaft isolator failing ?

 

I'd imagine if it had failed to the point of making that much noise it would be noticeable while driving and not just audibly. Still a good thing to check.

 

I took a look at the front driveshaft no movement whatsoever U joints on both ends look solid. Also checked out the exhaust system and found what I suspect is the source of the rubber smell, one of the wire sheathes on my O2 sensor has leaning against the pipe leading to the cat and had melted. Luckily I was planning on replacing the O2's anyway and have a set on hand. Didn't find anything beyond that in terms of dignosing my initial problem.

 

So I might have found the source of the tick. Last night I was installing an inline thermostat and when I was raising the coolant resivoir I noticed (what I later learned was the secondary air hose from the pump to the cross tube) a hose was disconnected. I still have a bit of work to do on the thermostat so I havent't been able to test if this is the source of the noise, but could a disconnected secondary air hose be the source of the noise I described? I've never had a car with a secondary air system before so I'm still trying to grasp the reason for its existence and how it functions. I'm still struggling to understand why the noise goes away when I'm in park or neutral and the lack of related check engine codes.

It appears the hose disconnected because the plastic connector at the end of the hose on the pump side has seen better days (it still clips in but disconnects quite easily). The new part costs just under $200 from Atlantic British. Would I be doing something terrible if I secured the hose to the pump using electrical tape?

 

Tape is fine I used a zip tie on mine it just moves air

 

Yes, vacuum leaks cause ticks

 

I had a similar noise in my old '04 G4 truck. Couldn't hear it with the hood open. It didn't sound like the typical Liner ticking. I thought maybe it was my power steering pump as it used to whine until I replaced all of the fluid, but I suspected it was on its way out. I also figured it might just be an exhaust leak as that seems pretty common on these things.

I never did figure it out as I didn't have any codes and the truck drove fine. I sold the truck back in 2020 and the new owner hasn't mentioned anything.

Another '04 I had did have a slipped liner and I never heard a thing. I got a CEL one day at around 40K miles. Brought it to the dealer since it was still under warranty. A few months later I had a brand new engine replaced by LRNA...

Sorry, not much help. Good luck.